The present invention relates to a speed adjusting system, a control unit for such a system as well as a method for adjusting the speed of a vehicle. The invention relates more specifically to such a system comprising a gas adjusting means adjustable by means of an accelerator, a control unit for such a system and a method for adjusting the speed of a vehicle.
The speed limits prevailing on the roads aim at increasing road safety. Nevertheless it is common for vehicles to exceed the permissible speeds. It goes without saying that this is not satisfactory from the viewpoint of road safety.
For this reason, various systems have been developed to ensure that the prevailing speed limits are obeyed.
For example, German Published Application DE 19638900 discloses a system preferably for vehicles with diesel engines, said system comprising a speed limiting device which is activated in case a permissible speed is exceeded. The speed is adjusted by pressing an accelerator for controlling a pump for fuel injection to the engine. The speed limiting device is, on activation, arranged in such manner that, independently of the position of the accelerator, the pump adjusts the fuel injection so that the speed of the vehicle does not exceed the permissible speed.
Moreover, German Published Application DE 2836342 discloses a system for vehicles, which system comprises a speed limiting device which, in case a permissible speed is exceeded, is activated in such manner that a coupling rod arranged between an accelerator and a throttle is extended, thereby reducing the speed provided by pressing down the accelerator. When the speed of the vehicle has been reduced to the necessary extent, the rod is retracted, whereby the speed of the vehicle can again be adjusted by operating the accelerator.
When these prior-art systems are activated, it is thus not possible to increase or even maintain the current speed, which of course in some cases can be disadvantageous or even dangerous, such as in overhauling.
When the above-described prior-art systems for adjusting the speed of a vehicle to the permissible speed are activated, the driver thus loses his capability of controlling the speed. The driver""s only way of avoiding this is to accurately observe on a speedometer the speed with which he drives his vehicle, and thereby ensure that this speed is at all times below the permissible speed.
A solution to this problem is disclosed in e.g. DE 2444518. The described system comprises a means for returning the accelerator, said means being activated if a permissible speed is exceeded. The accelerator can, however, still be pressed down, which requires an extra effort. It will thus be possible to drive the vehicle at a speed above the permissible maximum speed. However, the accelerator will be difficult to operate, which probably means that the driver chooses to lower the speed of the vehicle for the accelerator again to be easily operated.
Also the system according to DE 2444518 relates to a system which is not activated until a permissible speed has been exceeded. Thus, there is a need for a system which can be used to better promote the adjustment of the speed of a vehicle, i.e. a system which helps to ensure that the current speed limits are obeyed.
A first object of the present invention thus is to provide an improved system for adjusting the speed of a vehicle. The system should be designed so that it can be used to adjust the speed of a vehicle to a currently prevailing permissible maximum speed. More specifically, the system should promote such adaptation of the speed and at the same time allow driving of the vehicle at a speed exceeding the currently prevailing permissible maximum speed.
It is also advantageous if the system is designed in such manner that it draws the driver""s attention to the speed which is the currently permissible maximum speed.
A second object of the present invention is to provide a device which can be arranged in a system for adjusting the speed of a vehicle, said device being designed so as to promote adaptation of the speed of the vehicle to the currently permissible maximum speed.
A third object of the present invention is to provide an improved method for adjusting the speed of a vehicle, said method promoting adaptation of the speed of the vehicle to the permissible speed while the driver of the vehicle has the possibility of choosing to drive his vehicle at a speed exceeding the currently permissible maximum speed.
More specifically, according to the invention a speed adjusting system for vehicles is provided, comprising an accelerator, such as a throttle pedal, a speed adjusting means, such as a throttle or a fuel injection pump, which is adjustable by operating the accelerator, and a control unit which is connected to the accelerator and which is settable between a first operating position, in which the accelerator is operable without difficulty and a second operating position, in which the accelerator is operable with difficulty, said system being characterised in that the second operating position is a basic state of the control unit, the difficulty, with which the accelerator is operable when the control unit is arranged in said basic state, appearing as a resistance which is generated by the control unit and acting on the accelerator and which must be overcome for operating the accelerator and which clearly exceeds the resistance that exists for operating a conventional accelerator, and that the control unit comprises a drive means, the drive means, on activation, being adapted to counteract said resistance, which control unit will thus be arranged in its first operating position through activation of the drive means.
Thus a system is provided, which can be used to promote adaptation of the speed of the vehicle so that a permissible maximum speed is not exceeded while the driver of the vehicle always has the possibility of driving his vehicle at the desired speed.
The control unit is suitably arranged in its first operating position for driving the vehicle at a speed which is lower than or corresponds to a currently prevailing permissible maximum speed and in its second operating position when exceeding said permissible maximum speed. Thus, a system is provided, which when exceeding a permissible maximum speed makes the accelerator difficult to operate. The driver can choose either to reduce the speed, in which case the control unit is arranged in its first operating position when the speed falls below the permissible speed-which makes the accelerator once more easy to operate-or to maintain or even increase the speed, in which case the control unit will remain in its second operating position-whereby the accelerator remains difficult to operate. The system thus is satisfactory in terms of road safety since the driver all the time keeps control of the vehicle. At the same time it is, of course, most favourable for the driver to drive the vehicle at a permissible speed since this makes the accelerator easier to operate.
A particularly advantageous effect obtained in the inventive system is that the driver""s attention is at all times attracted to the speed which is the permissible maximum speed. This is achieved by the driver, when operating the accelerator, senses a final position of the accelerator, in which final position the throttle pedal will be stiff to operate. It will thus be extremely simple for the driver to drive the vehicle at the permissible speed by always seeing to it that the accelerator is never moved past said final position. The final position is provided by the drive means, which in the first operating position of the control unit counteracts the resistance acting on the accelerator. Thus the drive means will assist in operating the accelerator as long as the control unit is arranged in its first operating position. This assistance ceases immediately when the control unit is arranged in its second operating position, which, as mentioned above, suitably corresponds to the driving of the vehicle at a speed exceeding the permissible maximum speed. Operation of the accelerator with assistance is thus allowed to a certain extent. Continued operation thus occurs without assistance and requires an increased effort. Consequently the permissible maximum speed will be clearly perceptible to the driver in the form of a final position when operating the accelerator.
The inventive system will also be extremely reliable and safe. In case of damage or malfunction in the system, the only consequence will be that the control unit is arranged in its non-activated basic state corresponding to the second operating position. The accelerator will thus be difficult to operate in case of malfunction. This eliminates the risk of locking the accelerator to a nondesirable extent.
Preferably, the control unit is arranged for gradual setting from one of the first and the second operating position to the other of the first and the second operating position.
Preferably the system comprises a controller, which is adapted to receive information about the speed of the vehicle and the current speed-limit regulations from a monitoring system; and to control the control unit on the basis of the information received from the monitoring system.
According to a preferred embodiment of the system, the control unit is also connected to the speed adjusting means, the control unit being arranged in such manner that the speed adjusting means is adjustable via the control unit by operating the accelerator.
Moreover, according to the present invention, a control unit is provided for adjusting the speed of a vehicle, comprising a first arm turnable by means of an accelerator, a second turnable arm, and a third arm turnable with the aid of a drive means, said first arm being spring loaded in such manner that, for turning thereof, a first force must be applied thereto, and said second arm being spring loaded in such manner that, for turning thereof, a second force must be applied thereto, the first arm, after turning through an angle, being arranged for engagement with and co-turning of the second arm, whereby, for turning of the second arm by operating the accelerator, this must be operated by applying a force corresponding to the sum of the first force and the second force, the third arm, on turning, being arranged for engagement with and co-turning of the second arm and the drive means, on activation, being arranged for such turning of the third arm and, thus, also of the second arm that the angle between the first arm and the second arm is maintained upon turning of the first arm.
As a result a control unit is provided, which is extremely suitable for use in a system according to the present invention. When the drive means is activated, a turning, caused by e.g. a throttle pedal, of the first arm will cause a suitable turning of the second arm for maintaining the angle between the arms. The first arm will thus not engage with the second arm, whereby the throttle pedal need only be operated with the first force for adjusting the speed. When the drive means is switched off or deactivated, said angle will not be maintained, and thus the throttle pedal must be subjected to a force corresponding to the sum of the first and the second force. By seeing to it that this sum is sufficient, it is possible to ensure that the operation of the throttle pedal will be difficult. It is thus suitable to arrange the control unit in such manner that it is switched off in case the speed is exceeded, thereby promoting driving of the vehicle at a permissible speed.
The second arm of the 1control unit can be connected with a speed adjusting means, whereby the speed adjusting means can be adjusted by turning of the second arm.
Finally, according to the present invention a method is provided for controlling the speed of a vehicle, comprising the steps of arranging an accelerator in such manner that it can only be operated with difficulty to adjust a speed adjusting means, counteracting, by means of a control unit, said difficulty to such an extent that it is essentially eliminated, and ceasing, if the vehicle is driven at a speed exceeding a currently prevailing permissible maximum speed, to counteract said difficulty, whereby the exceeding of the speed is made evident to the driver of the vehicle in such manner that the accelerator can be operated only with difficulty to adjust the speed adjusting means.